System and method for driving electronic shutter of a camera

ABSTRACT

As for a camera, a method for driving an electronic shutter of a camera, comprising the stages of setting an initial focus of a rotating member connected with a focus control lens in a state where the focus control lens is pre-set in a middle position between a maximum zoom position and a minimum zoom position, such that the initial position of a focus control lens is positioned in a middle step between a focus position of the focus control lens with respect to a pre-set farthest subject and a focus position of the focus control lens with respect to closest subject; controlling focus by rotating the rotating member connected to a first driving means from an initial position to a clockwise or counterclockwise direction, in order to move the focus control lens to a position set according to a value calculated by a distance measuring means when a shutter switch is operated; and performing exposure by sector opening/closing means being operated according to an exposure value calculated by a luminescent measuring means, connecting sectors, which are biased through an elastic member, with second driving means rotating in both directions, depending on the application of electrode, when controlling focus of the focus control lens is finished.

BACKGROUND OF THE INVENTION

The present invention relates to a system and method for driving anelectronic shutter of a camera, and more particularly, to a system andmethod for driving an electronic shutter of a camera in which electronicshutter responsiveness is quick and the structure of the electronicshutter is simple.

FIELD OF THE INVENTION

Generally, the electronic shutter of a camera is structured such that itautomatically connects an automatic focus control, which controls thezooming of a lens for focus control to a measured distance of a subject,and an automatic exposure control, which matches and controls an irisand shutter speed according to an appropriate amount of exposure for thesubject.

The above electronic shutter for cameras is proposed in U.S. Pat. Nos.4,918,480, 4,634,524, and 5,111,230 and Japanese patent No. 61-9632.

The above prior art have in common a focus control ring, which controlsthe zooming in/out of the lens for focus control according to themeasured distance of the subject, and a locking device, which stops therotation of the focus control ring when the lens for focus control hasreached the focus location.

Also included are sector open/close means, which open and close a sectoraccording to a suitable amount of exposure for the subject; an exposurecontrol ring, which operates the sector open/close means to its fixedlocation; an initial fixed position control device, which returns thefocus control ring and exposure control ring to a fixed positionimmediately following exposure; and a power source which operates thefocus control ring and the locking device.

In the prior art as in the above, with regard to the zoom controldriving method of the lens for focus control, the focus control ringgradually moves the lens for focus control from a minimum zoom locationto a maximum zoom location and vice versa.

In the above, the minimum zoom location indicates the focus location ofthe lens for focus control in which the subject is at the farthestdistance, and the maximum zoom location refers to the focus location ofthe lens for focus control in which the subject is at the closestdistance.

Referring to FIG. 29, a driving sequence of an electronic shutter ofU.S. Pat. No. 5,111,230 is illustrated. As can be seen in the drawing,the lens for focus control is zoomed out from the minimum zoom location(j) to the maximum zoom location (k) by the focus control point. Afterthe lens for focus control is zoomed out to the measured distance (l),it is returned in the opposite direction to the minimum zoom location(j).

Recently, in order to improve the focus control functions of theelectronic shutter, focus control steps are used from the minimum zoomlocation to the maximum zoom location are further multiplied.

Resulting from this use of further multiplied steps is the increase infocus control time, slowing the responsiveness of the electronicshutter.

That is, if the first step of the focus control ring uses X!ms amount oftime, the time required to go from the beginning to the end (from theminimum zoom control location to the maximum zoom control location orvice versa) is the maximum step No. X!ms amount of time, which uses anexcessive amount of time for focus control.

Also, in the prior art electronic shutter, a locking device is neededfor stopping the rotation of the focus control ring when the focuscontrol lens is zoomed out according to the measured distance of thesubject, resulting in a complicated structure.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to solve the aboveproblems.

It is an object of the present invention to provide an electronicshutter driving method and device for a camera which, by shortening themoving distance of a focus control lens, zooming the focus control lensout according to a measured distance of a subject, and thereforereducing the amount of time used for focus control, improves theresponsiveness of an electronic shutter.

It is another object of the present invention to provide an electronicshutter driving method and device for a camera which, by eliminating theuse of a locking device, employed for stopping the rotation of a focusring when focus control is completed, attains a simpler structure andoperational stability.

The above objects are realized in accordance with the present inventionwhich provides an electronic shutter driving method in which an initialfocus of a rotating member connected with a focus control lens is set ina state where the focus control lens is pre-set in a middle positionbetween a maximum position and a minimum position of a whole focusingregion. The initial position of a focus control lens is positioned in amiddle step between a focus positions of the focus control lens withrespect to a pre-set farthest subject and a focus position of the focuscontrol lens with respect to closest subject. And then, focus iscontrolled by rotating the rotating member connected to a first drivingmeans from an initial position to a clockwise or counterclockwisedirection, in order to move the focus control lens to a position setaccording to a value calculated by a distance measuring circuit when ashutter switch is operated. Finally, exposure is performed by sectoropening/closing means being operated according to an exposure valuecalculated by a luminescent measuring circuit, connecting sectors, whichare biased through an elastic member, with second driving means rotatingin both directions, depending on the application of current, whencontrolling focus of said focus control lens is finished.

According to another aspect of the present invention, a system fordriving an electronic shutter of a camera comprises a first drivingmeans including a power supply and a rotation member meshing with saiddriving means, rotating in the same direction as the power supply, andzooming the focus control lens in response to a value calculated by adistance measuring circuit. Means for detecting and adjusting theinitial position adjusts said rotation member to an initial positionwhen said rotation member is not positioned in a middle position betweenthe maximum zooming position and the minimum zooming position, wheninitial power supply is applied to the camera. Second driving means,opening/closing sectors are driven according to an exposure valuecalculated by the luminescent measuring circuit when a power supply isapplied, while keeping sectors closed, biased by the elastic member.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate an embodiment of the invention,and, together with the description, serve to explain the principles ofthe invention:

FIG. 1 is a view illustrating an electronic shutter driving method of acamera according to the present invention;

FIG. 2 is an exploded perspective view illustrating an electronicshutter driving device for cameras according to a first embodiment ofthe present invention;

FIG. 3 is a longitudinal sectional view illustrating first driving meansaccording to a first embodiment of the present invention;

FIG. 4A is a bottom view illustrating first and second driving meansaccording to a first embodiment of the present invention;

FIG. 4B is a perspective view showing an elastic member of FIG. 4A;

FIGS. 5 and 6 are respectively a longitudinal sectional view and a planview illustrating a focus control lens and a rotating member in a mergedstate according to a first preferred embodiment of the presentinvention;

FIG. 7 is a longitudinal sectional view of a lens barrel support deviceaccording to a first preferred embodiment of the present invention;

FIG. 8 is a plan view illustrating a sector according to a firstpreferred embodiment of the present invention;

FIG. 9 is a view illustrating initial position detecting means accordingto a first preferred embodiment of the present invention;

FIG. 10 is a flow chart of an initial position detecting methodaccording to a first preferred embodiment of the present invention;

FIG. 11 is a view illustrating an initial position of a power sourceaccording to a first preferred embodiment of the present invention;

FIG. 12 is a view illustrating an exposure starting point of a sectoraccording to a first preferred embodiment of the present invention;

FIGS. 13A to 13D are views illustrating a port reflector error signalaccording to a first preferred embodiment of the present invention;

FIGS. 14A and 14B are views of a electronic shutter driving system forcameras according to a second preferred embodiment of the presentinvention;

FIG. 15A, is an exploded perspective view of an electronic shutterdriving device shown in FIG. 14;

FIG. 15B is an assembled view of FIG. 15A;

FIG. 16 is a side sectional view of an electronic shutter driving systemaccording to a second preferred embodiment of the present invention;

FIG. 17 is a plan view of a focus control cam applied to an electronicshutter driving device according to first and second preferredembodiments of the present invention;

FIG. 18 is a view illustrating an exposure chart of an electronicshutter according to a second preferred embodiment of the presentinvention;

FIG. 19 is a side sectional view illustrating a position relationshipbetween a focus ring and an exposure ring and a magnet according to asecond preferred embodiment of the present invention;

FIG. 20 is a view illustrating a position relationship between a sectorand an open lever according to a second preferred embodiment of thepresent invention;

FIG. 21 is a view illustrating a state in which an electronic shutterdriving device opens a sector according to a second preferred embodimentof the present invention;

FIGS. 22A, 22B, 22C and 22D are views illustrating a step motor drivingstate of a fixed point control type used in a electronic shutteraccording to a second preferred embodiment of the present invention;

FIG. 23 is a flow chart of normal exposure for explaining an electronicshutter driving control method according to a second preferredembodiment of the present invention;

FIG. 24 is a flow chart of bulb exposure for explaining an electronicshutter driving control method according to a second preferredembodiment of the present invention;

FIG. 25 is a view illustrating general exposure when an exposure controlring rotates clockwise for explaining an electronic shutter drivingmethod according to a second preferred embodiment of the presentinvention;

FIG. 26 is a view illustrating general exposure when an exposure controlring rotates counterclockwise for explaining an electronic shutterdriving method according to a second preferred embodiment of the presentinvention;

FIG. 27 is a view illustrating bulb exposure when an exposure controlring rotates clockwise for explaining an electronic shutter drivingmethod according to a second preferred embodiment of the presentinvention;

FIG. 28 is a view illustrating bulb exposure when an exposure controlring rotates counterclockwise for explaining an electronic shutterdriving method according to a second preferred embodiment of the presentinvention; and

FIG. 29 is a view illustrating a driving sequence of a prior electronicshutter.

DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

Referring to FIG. 1, reference letter (a) refers to an initial positionof a focus control lens. The initial position (a) of the focus controllens is fixed between a minimum zoom position (b) and a maximum zoomposition (c), and by first driving means, a focus lens is zoomed outaccording to a measured distance value, measured by a distance-measuringcircuit.

In the above, assuming that the total number of steps of the aboveautomatic focus control is 40 steps, the initial position (a) is a 20thstep, the maximum zoom position (c) is the 40th step and the minimumzoom position (b) the 1st step.

More specifically, the electronic shutter driving method of the presentinvention fixes the initial position (a) of the focus control lens zoomat the starting point of the automatic focus position control, and byrotating a rotation member, connected to the lens, either in a clockwise(CW) or a counterclockwise (CCW) direction, performs an automatic focuscontrol of the focus control lens.

As a result, the present invention reduces zooming time, when going fromthe minimum zoom position to the maximum zoom position and vice versa,to a level of at least half that of the prior art.

FIGS. 2-8 will now be referred to explain an electronic shutter drivingsystem for cameras of the present invention operating as in the above.

In FIG. 2 illustrating a whole electronic shutter driving device forcameras according to a preferred embodiment of the present invention,reference numeral 1 refers to a power source of first driving means.This power source 1 is comprised of a motor gear 3, formed integrallywith four permanent magnets (PM), and a pair of stators 5.

When driving, the power source 1 can rotate 90° at a time in theclockwise or counterclockwise direction by the four permanent magnets.The power source 1 is located at a motor base (B), and a motor cover (C)is connected to its upper side.

Also, the first driving means includes a speed reduction gear portion,meshed with the power source 1 and which transmits rotative force. Thespeed reduction gear portion is illustrated in FIGS. 3, 4A, and 4B inmore detail and comprises a plurality of gears 7, 9, and 11 engaged witheach other.

The gear 7 is meshed with the motor gear 3 of the power source 1, andthe gear 11 is meshed with a focus control ring 13, connected to thefocus control lens. The speed reduction gear portion is located at ashutter base (S) and is connected to the lower part of the motor base(B).

As shown in FIG. 5, a helicoid (H) is formed on the inner circumferenceof the focus control ring 13, which is connected to a lens holder 15.The lens holder 15 is integrally connected with a lens barrel 17.

The focus control ring 13 is rotatably supported between the shutterbase (S) and the motor base (B).

As shown in FIG. 6, a rotation preventing protrusion 19, formed on theoutside of the lens holder 15, is inserted in the motor cover (C) suchthat it is tightly fitted with a rotation preventing groove 21.

Therefore, according to the rotating direction of the focus control ring13, connected to the power source 1, the lens holder 15 moves in an upand down direction along the rotation preventing groove 21 formed on themotor cover (C) when viewing FIG. 5.

Coil springs 23, which act as elastic members, are interposed betweenthe lens barrel 17 and the motor cover (B), and they prevent freemovement caused by the meshing of the focus control ring 13 and the lensholder 15 (see FIG. 2).

As shown in FIG. 7, the lens barrel 17 interposes the coil spring 23between a groove 25 formed in a protrusion 29 of the lens barrel 17 anda pin 27 formed on the motor cover (C), and, in this way, the lensbarrel 17 is structured to always receive force in the upward direction(in the drawing).

In addition, the electronic shutter of the present invention includesinitial position detecting and regulating means for adjusting the focuscontrol ring 13 to the initial position when the electronic circuitportion is turned on from an off state and after it is detected that thefocus control ring 13 is not in the predetermined initial position, orwhen the shutter begins its operation after the distance of the subjectand the exposure value has been calculated when the shutter switch isoperated.

As can be seen in FIG. 4A, the initial position detecting and regulatingmeans comprises a protrusion 131, a gear portion 132 (formed on thefocus control ring 13), and a photo interrupter 31.

When the protrusion 131 of the focus control ring 13 is not in theinitial position, the photo interrupter 31 sends a signal to the powersource 1 to rotate the focus ring 13 in a clockwise direction until itreaches the initial position.

In addition to having an automatic focus device, the electronic shutterdriving device of the present invention also includes an automaticexposure control device.

This automatic exposure device has an automatic exposure meter 41 as aseparate driving means which is a second driving means.

Referring to FIGS. 2, 4A and 4B, the automatic exposure meter 41includes a boss 43, which rotates in one direction or the otheraccording to the direction in accordance with an electric currentapplying direction.

The boss 43 is engaged with a catch projection 47 of the gear lever 45,which is supported by a shutter base (S) so that it can rotate. Anelastic member 49 is fixed on the gear lever 45 and is elasticallysupported by the shutter base (S).

As a result, the automatic exposure meter 41 always receives elasticforce in the counterclockwise direction, and when it is rotated in theclockwise direction, it does so pushing against the elastic force of theelastic member 49.

As can be seen in FIG. 4B, the elastic member 49 has elastic force in acircumferential direction, and a plurality of turns (T) forming theelastic member 49 create elastic force also in an up-down (vertical)direction.

The elastic member 49 applies elastic force to a sector lever 51 so thata sector can always stay in a closed state.

As the bounce of the gear lever 45 and sector lever 51 can be absorbedby this structure, double opening of the sector can be prevented.

Also, the gear lever 45 is meshed with the sector lever 51, which isjoined with the shutter base (S) such that it can rotate, and the sectorlever 51 has a sector pin 53 and is joined simultaneously with twosectors 57 and 59.

Through this structure, the sectors 57 and 59 are biased by the elasticmember 49 in closed states. While rotating in a clockwise direction, theautomatic exposure meter 41 pushes against the force of the elasticmember 49 and opens the sectors 57 and 59.

As shown in FIGS. 2 and, 8, the sectors 57 and 59 are structured in theconventional manner, secured and supported in the shutter base (S) andjoined with a sector cover (SC) on their lower sides.

A slot 61 is formed on at least one side of the sector 57, and the slot61 is detected by a photo reflector 63 fixed on the shutter base (S),and through this detection, a starting point of automatic exposurecontrol is established.

That is to say, the sectors 57 and 59 open as shown in the broken lines57' and 59' by the clockwise rotation of the automatic exposure meter41. At this point, the photo reflector 63 recognizes the opened startingpoint of the sector 57 and allows for the control of the exposure valuecalculated by the light-measuring circuit portion.

Based on the electronic shutter driving device as explained above, theelectronic shutter driving method and operation of this embodiment willnow be explained.

First, an initial position is established so that the initial positionof zoom in/out of the focus control lens is located in the central stepof all the automatic focus control steps.

At this point, the initial position detecting and regulating meansdetects the position of the focus control ring 13, connected to thefocus control lens, and controls the initial position.

The above operation will now be described with reference to FIGS. 9 and10.

After the shutter switch is operated, the distance-measuring circuitportion and the light-measuring circuit portion calculate the distanceand exposure values of the subject. Next, when either the shutter startsin response to the calculated values, or the power is turned on in theelectronic circuit portion, the power source 1 rotates clockwise and, asshown in FIG. 9, the focus control ring 13 also moves clockwise.

At this time, if it is supposed that the positioning of the photointerrupter 31 at the gear portion 132 of the focus control ring 13 isat an initial position, the CPU (not shown) clears a counting means,which counts the number of drive pulse signals, to `0` and determineswhether the present state of the photo interrupter 31 is at `H` or `L`.

In the above, `H` represents a state when the signal of a luminescentportion is cut off and not reaching a photoelectric portion, and `L`represents a state where the signals of the luminescent portion reachesthe photoelectric portion and when they both output signals.

Next, a clockwise drive pulse is applied to the photo interrupter 31 andit is determined again whether the photo interrupter 31 is at `H` or`L`. If it is in the same state, the counter means is added by "1" (stepS4), and if the photo interrupter 31 is not in the same state, thecounter is cleared to `0`.

Here, because the photo interrupter 31 is positioned in the gear portion132 of the focus control ring 13, even if a clockwise drive pulse isapplied, the counter means is repeatedly cleared to `0`.

If the photo interrupter is positioned in the protrusion 131 of thefocus control ring 13 by the above clockwise drive pulse, the countermeans determines if the value is above a pre-set fixed value (forexample, 8) (step S6) and it is determined if the state of the photointerrupter 31 is in an `H` state.

At this time, if it is determined that the state of the photointerrupter is in `H`, it is recognized that the present location of thefocus control ring 13 is at its protrusion 131, a clockwise drive pulseis applied, and the time when the state of the photo interrupter 31 ischanged from `H` to `L` is detected (steps S8 and S9).

Finally, a circuit (not shown) checks if the power application state ofthe step drive power source 1 is in the initial position, as shown inFIG. 11, and the power is turned off in this state.

However, if the state of the step drive power source 1 is not identicalto that shown in FIG. 11, a clockwise drive pulse is continuallyapplied, the power is turned off after reaching a state of that shown inFIG. 11, and the focus control ring 13 is controlled to the initialposition.

Next, the step drive power source 1 depicted in FIG. 11 determines ifthe first and third coils are in the `H` state (step S10), and if theyare, power is turned off.

As one step of the step drive power source 1 is composed of two drivepulses, the determination of two `H`s or two `L`s is possible duringdriving by one step.

When the photo interrupter 31 is located in an open portion 133 of thefocus control ring 13, the circuit (not shown) clears the means, thatcounts the number of drive pulse signals, to `0`, operates the photointerrupter 31, and determines if its present state is in `H` or `L`.

If it is detected to be in `L`, the above counter means rotates the stepdrive power source 1 in the clockwise direction until it surpasses afixed value (for example 8).

In the above, the rotating of the step drive power source 1 by thecounter means until it passes a fixed value is for the precisedetermination of the position of the focus control ring 13 when initialposition of the step drive power source 1 is not in a position as thatshown in FIG. 11.

The circuit (not shown) detects the present location of the focuscontrol ring 13 at the open portion 133 by the continuous clockwiserotation of the counter means until it is past the fixed value, and thedrive pulse is reversed so that the step drive power source 1 rotates inthe counterclockwise direction (step S11).

By the reverse drive pulse, the focus control ring 13 rotatescounterclockwise, and it is determined if the initial state of the photointerrupter 13 has changed from `L` to `H`, and if it has, control tothe above step (S10) is realized.

After the circuit (not shown) detects the point of change, it convertsthe drive pulse to a normal pulse, rotates the focus control ring 13clockwise, and the focus control ring 13 is controlled to its initialposition as in the first method above.

After the initial position of the focus control lens and focus controlring 13 is established, according to the shutter switch operation, thefocus control lens is zoomed out to an automatic focus location,determined by the distance-measuring circuit, thereby performingautomatic focus.

At this point, the focus control lens 13 is moved to the maximum orminimum zoom location according to the direction in which the powersource 1 rotates the focus control ring 13.

The focus control lens is integrally joined with the lens holder 15, andbecause the lens holder 15 is prevented from rotating by the motor covermember 20, the rotating operation of the focus control ring 13 moves thefocus control lens in a linear direction.

That is to say, the focus control ring 13 is rotated in the clockwisedirection (see FIG. 4) through the use of the speed reduction gearportion by the power source 1, the focus control lens is zoomed towardthe sector side (toward the bottom in FIG. 5), and zoomed toward thesubject when the focus control ring 13 is rotated in thecounterclockwise direction.

Here, the power source 1 is rotated by 90° when driven in one step andthe focus control ring 13 is also rotated in the same amount. Inaddition, the focus control ring 13 comes to have many focus controlsteps.

At the time focus control is completed, as the power source 1 has atleast a 20 ms stabilizing interval, an over-run phenomenon is prevented.

Also, at the time focus control is completed, automatic exposure isperformed according to the exposure value calculated in thelight-measuring circuit portion by the second drive means. Here, theautomatic exposure meter 41, as the second drive means, rotatesclockwise (in FIG. 4A) while overcoming the elastic force of the elasticmember 49 according to the application of an electric current, and bythe rotation of the gear lever 45 and the sector lever 51, connected tothe automatic exposure meter 41, the sectors 57 and 59 are opened.

At this time, to precisely control the opening time (amount of exposure)of the sectors 57 and 59, the present invention detects the beginningpoint of exposure. This detection is realized through the photoreflector 63, recognizing the slot 61 location of the sector 57. Thisoutput signal is shown in FIG. 12.

Namely, since the photo reflector 63 generates two high pulse signalsand two low pulse signals corresponding to the slot 61 of the sector 57,one of either is used as an exposure starting point, and, by doing so, aprecise amount of exposure can be controlled.

Error signals of the photo reflector 63 appear in FIGS. 13A, 13B, 13Cand 13D.

As is illustrated, when the signal of the photo reflector 63 appears asone of the signals (I), (II) (III) and (IV) of the photo reflector 63shown in FIGS. 13A-13D, respectively, a control circuit (not shown)determines that the state is an error state and indicates an errormessage to an indication device.

On the other hand, as the sectors 57 and 59 close when the automaticexposure meter 41 receives an opposite electrical current, the elasticmember 49 rotates the gear lever 45 in the counterclockwise direction byits elastic force.

Second Embodiment!

The description hereinafter is an electronic shutter drive system andmethod according to a second embodiment of the present invention withreference to FIGS. 14 to 29.

Referring first to FIGS. 16 and 17, a lens barrel 204 is located in theinner part of a shutter base 202 and also in a focus control cam barrel206, and it is structured so that it can zoom out/in in the direction ofthe cam barrel axis according to the rotation amount and direction ofthe focus control cam barrel 206.

This lens zooming is generally realized by the movement of the lensbarrel in response to the cam curvature. The focus control cam barrel206 of the preferred embodiment includes a cam portion 208.

The cam portion 208 includes a horizontal portion 210, corresponding tothe initial position; a first cam portion 212, which extends toward thefront from the horizontal portion 210 following the inside face of thefocus control cam barrel 206; and a second cam portion 214, whichextends toward the rear from the horizontal portion 210 following theinside face of the focus control cam barrel 206.

A fork 216 is formed on one side of the focus control cam barrel 206.The fork 216 is a means for receiving the rotating force of the focuscontrol ring 218, fixable to rotate on the outer circumference of theshutter base 202.

The focus control ring 218 includes a pin 220 joined with the fork 216,and teeth 222 are formed around roughly 1/2 the outer circumference ofthe focus control ring 218. Also, a protrusion 223 is formed extendingoutward on the outer circumference of the focus control ring 218.

The final gear of the speed reduction portion 224 is meshed with theteeth 222 and is structured so as to enable receiving of the rotationalforce by a stepping motor (M).

The speed reduction portion 224 receives rotational force from a singlepower source and comprises a gear train for first dividing andtransmitting this rotational force to the focus control ring 218 andexposure control ring 228.

As a result, the speed reduction portion 224 has a speed reduction gear230 for exposure control, and a plurality of speed reduction gears 232a,232b, 232c, 232d, and 232e for focus control. A motor gear 234 is alsoprovided which is a two-level gear. Because of its structure, the motorgear 234 is joined to both the reduction gear 230 and the plurality ofreduction gears 232a-232e.

Through the above gear arrangement, the teeth 222 are meshed with thespeed reduction gear 232e which is the final gear of the speed reductionportion 224, and receive rotational force.

The first speed reduction gear 232a is comprised of an upper portiongear 232a-1 and a lower portion gear 232a-2 and, as shown in FIG. 14B,are fixed having an interval from a shaft (S) and able to rotate.

The above shaft (S) is rotatably structured having a fixed interval withthe upper and lower gears 232a-1 and 232a-2.

Time-difference protrusions 236 and 238 are formed on the lower gear232a-2 at an angle corresponding to one step. A slide protrusion 240 isformed on the upper gear 232a-1 and disposed between the time-differenceprotrusions 236 and 238.

The upper gear 232a-1 of the speed reduction gear 232a meshes with anadjacent speed reduction gear 232b so as to be able to transmit powerthereto. The lower gear 232a-2 meshes with a motor gear 234 so as toreceive the rotating force of the stepping motor.

The exposure control ring 228 is provided on its outer circumferencewith a plurality of protrusions 229' and a plurality of protrusions 231'which are arranged between the protrusions 229'. The protrusions 229'and 231' are arranged at an angle of 22.5 degrees. The protrusions 231'are respectively provided with extension ends 235' extending outward.

The exposure control ring 228 and the focus control ring 218 areconcentrically disposed and relatively rotatable. On one peripheryportion of the rings 228 and 218, a sector opening/closing means isprovided to open and close the sectors.

The sector opening/closing means according to this embodiment comprisesa sector close lever 246 rotatably coupled on the shutter base 202 by apin 250, a sector open lever 248 rotatably coupled on the shutter base202 by a pin 252, and elastic members 254 and 256 for respectivelyapplying clockwise rotating force to the sector close lever 246 and thesector opening lever 248.

One end of each of the elastic members 254 and 256 is hooked on theshutter base 202, and each of the other ends thereof are respectivelyhooked on the sector close lever 246 and the sector open lever 248.

There is provided a governor means on one side of the sector open lever248 to control the exposure. In this embodiment, the governor meanscomprises a worm gear 258 integrally formed on one end of the lever 248,a wormwheel 260 meshing with the worm gear 258, a governor gear 262disposed on a common axis with the wormwheel 260 to be rotatablytherewith, and an anchor 264 which is to be hooked on the governor gear262.

The wormwheel 260, the governor gear 262 and the anchor 264 are allrotatably coupled to the shutter base 202.

As shown in FIG. 19, the other end of the sector open lever 248 isconnected by a pin 266 to the pair of sectors S1 and S2 so that it canopen and close the sectors S1 and S2.

The sector close lever 246 is restrained or unrestrained by a magnet268. That is, when electric power is applied to the magnet 268, thelever 246 is restrained, and when not applied to the magnet 268, thelever 246 is unrestrained.

This operation is realized by providing a sector close pin 270 on thesector close lever 246 so that the pin 270 can be located in a groove274 of a restrain member 272 which is reciprocated by the magnet 268.

In this embodiment, the step motor M used as a drive source for drivingthe motor gear 234 in a positive or negative direction is divided intofour sections at an angle of 90 degrees and has a magnetized rotor R(see FIGS. 22A, 22B, 22C and 22D).

The step motor M is applied with electric power at a speed of at least20 m/s so as to obtain magnetic field stabilization before the electricpower is turned off.

The above-described electronic shutter drive system according to thisembodiment performs automatic focus control of the lens according to thedrive process as shown in FIG. 9.

First, after an initial position of the focus control lens isestablished at a mid-step between the farthest zoom position (b) and theclosest zoom position (c), a distance measuring circuit calculates thedistance value of the object, and in response to the measured value, thefocus control lens is zoomed out/in by the driving means.

Here, assuming that the total number of steps of the automatic focuscontrol is 40 steps, the initial position of the focus control lensbecomes the 20th step, the farthest zoom position (b) becomes 1st step,and the closest zoom position (c) the 40th step.

The initial position (a) of the lens is established by positioning a camfloor F of the lens barrel 204 on the horizontal portion 210 of the camportion 208, or alternatively, by a method for controlling a focuscontrol ring disclosed in Korean patent application No. 95-33888 filedby the present assignee, which is hereby incorporated by reference.

Therefore, since the initial position (a) is set as a starting point ofthe automatic focus control and the focus control ring connected to thelens is driven in a clockwise or counterclockwise direction, the focuscontrol time can be shortened. This will be described more in detailhereinafter.

When the shutter starts to operate after completing light-measurementand distance-measurement, electric power is applied to the magnet 268and the restraining member 272 is attached to the magnet 268 such thatthe sector close lever 246 located in the groove 274 is restrained bythe sector close pin 270.

In this state, the step motor continues its rotation and the sector openlever 248 is released from the protrusion 223'. By this operation, thesector open lever 248 is biased by the elastic member 256 in a clockwisedirection in the drawing (see FIG. 19).

The clockwise rotating force transmitted to the sector open lever 248 isfurther transmitted to the worm gear 258 of the governor means androtates the wormwheel 260 together with the governor gear 262 so thatgoverning operation can be realized by the anchor 264.

That is, although the worm gear 258 intends to rotate by receivingrotating force from the sector open lever 248 via the wormwheel 260,since opposite ends of the anchor 264 are alternatively engaged with thegovernor gear 262, the rotation of the worm gear 258 is restricted.

As a result, the rotating speed of the sector open lever 248 becomesslower than that of the exposure control ring 228 as illustrated in agraph of FIG. 18.

At this point, the step motor, as shown in FIGS. 22A, 22B, 22C and 22D,rotates by an angle of 90 degrees at a time. By this rotation, the focuscontrol ring 218 rotates by a predetermined angle at a time, and theexposure control ring 228 rotates by one pitch (22.5 degrees) at a time.

However, since time is needed for the sector open lever 248 to bereleased from the protrusion 223' of the focus control ring 218, focuscontrol should not be performed during this period. Therefore, in thisembodiment, there is provided the horizontal portion 210 on the camportion 208 so that focus control cannot be performed during this time.

Now, an electronic shutter driving method during the clockwise rotationof the step motor will be described with reference to FIGS. 23 through28.

Immediately after the sector open lever 248 is released from theprotrusion 223 of the focus control ring 218 and when the focus controlring and the exposure control ring rotate clockwise and the steppingmotor rotates by four steps, a normal exposure method is as follows:

At the initial position(step S100), it is determined if the drivingdirection of the stepping motor M is a clockwise direction orcounterclockwise direction (step S110). If the driving direction is theclockwise direction, it is next determined if the driving step of thestepping motor is an odd number or even number (step S120). If thedriving step is an even number, as a step S130, the initial positionstarts as a position where the time difference protrusion 236 of thelower gear 232a-2 contacts the slide protrusion 240 of the upper gear232a-1.

Since the time difference protrusion 236 is in a contact state with thetime difference protrusion 240, the rotating force of the stepping motoris transmitted to the focus control ring 218, thereby rotating the focuscontrol ring 218 as much as the measured distance amount(4 steps).

At this point, the exposure ring 228 connected to the exposure speedreduction gear 230 receives a clockwise rotating force and moves by 4steps.

Although the sector open lever 248 receives a clockwise rotating forceabout the pin 252 while receiving rotating force from the stepping motorM and performing focus control, since the anchor 264 is engaged with thegovernor gear 262, the protrusions 229' and 231' of the exposure controlring 228 restrains the rotation of the sector open lever 248 before thesectors pivot to the open position. That is, the sectors are preventedfrom being opened during the focus control time.

This is done by restricting the movement of the sector open lever to theopen position since the angular velocity of the exposure control ring228 is higher than that of the sector open lever 248.

When completing the focus control by the above operation, the steppingmotor M rotates counterclockwise by 1 step to enable exposure controlwhile the sector close lever 246 is in a state where it cannot rotatesince it contacts the end 235' of the exposure control ring 228 (stepS150).

That is, the counterclockwise rotation of the stepping motor M by 1 steprotates the lower gear 232a-1 clockwise by 1 step so that the exposurecontrol ring 228 can rotate counterclockwise by 1 step in a state wherethe focus control ring 218 does not rotate, thereby releasing therestrain of the sector close lever 246.

At this point, although the sector close lever 246 is maintained in anattached state to the magnet 268, the sector open lever 248 rotates tothe open position by the elastic force of the elastic member 256 so asto open the sectors. After completing the exposure as described above,the magnet for exposure control is turned off so that the sector closelever 246 can be closed by the biasing force of the elastic member.

During this operation, the lower gear 232a-2 performs the focus controlby being rotated counterclockwise by 4 steps by the stepping motor M inresponse to the initial measured distance, and then rotates clockwise by1 step for exposure control. Therefore, the resultant number of rotatingsteps of the lower gear 232a-2 become 3 steps counterclockwise. Inaddition, the time difference 236 of the speed reduction gear isdisplaced toward the right from the initial left position.

That is, in a state where the focus control ring 218 rotates clockwiseby 4 steps, even when the lower gear 232a-2 rotates clockwise by 1 step,the focus control ring 218 does not rotate since the time differenceprotrusion 236 and the slide 240 is in a disengaged state.

Further, the exposure control ring 228 rotates clockwise by 4 steps andthen rotates counterclockwise by 1 step for exposure control. Therefore,the resultant number of rotating step of the exposure control ring 228become 3 steps clockwise.

After completing the exposure operation as described above, aninitialization of the shutter starts in accordance with a command of acontrol process unit (not shown).

The stepping motor rotates clockwise by 1 step to allow for the exposurecontrol ring 228 to freely rotate by rotating the sector close lever 246counterclockwise (step 160).

At this point, since the time difference protrusion 238 of the lowergear 232a-2 contacts the slide protrusion of the upper gear 232a-1, thefocus control ring 218 does not rotate while the exposure control ring228 rotates clockwise by 1 step. Therefore, from the initial position,each resultant rotation of both the focus control ring 218 and theexposure control ring 228 becomes 4 steps.

In this state, the magnet connected to the sector close lever 246 isturned on (step S170) and thereby the stepping motor rotatescounterclockwise by 5 steps so as to return the focus control ring 218to the initial position. In addition, by the rotation of the steppingmotor, the exposure control ring 228 which has been over-runcounterclockwise by 1 step rotates clockwise by 1 step to be returned tothe initial position, and the time difference protrusion 236 comes tocontact the slide protrusion 240, thereby completing the mechanicalinitialization of the shutter.

Since the exposure control ring 228 is in a state where it is rotated byfurther 1 step, the stepping motor is rotated in an opposite directionby 1 step so as to return the exposure control ring 228 to the initialposition, completing the initialization of the exposure control ring 228(step S180), and when the magnet is turned off (step S190), the controloperation is completed (step S200).

When the focus control ring and the exposure control ring rotateclockwise simultaneously and the stepping motor rotates by 7 steps, anormal exposure method is as follows:

The speed reduction gear 232a rotates counterclockwise by 7 steps (stepS130-1) in which the rotation of the focus control ring 218 is the sameas that of the exposure control ring 228 and the sector close lever 246is released from the exposure control ring. At this point, since themagnet 268 restrains the sector close lever 246, the sector close leverdoes not operate.

Accordingly, the sectors maintain their open state. The sectors areclosed when the exposure is completed and the magnet 268 is turned off.

The operation for initializing the sectors after completing the exposurewill be described hereinafter. An initialization of the shutter startsin accordance with a command of a control process unit (not shown).

The stepping motor rotates clockwise by 1 step to allow for the exposurecontrol ring 228 to freely rotate by rotating the sector close lever 246counterclockwise (step S160).

At this point, since the time difference protrusion 238 of the lowergear 232a-2 contacts the slide protrusion of the upper gear 232a-1, boththe focus control ring 218 and the exposure control ring 228 rotateclockwise by 1 step. Therefore, from the initial position, eachresultant number of rotating steps of both the focus control ring 218and the exposure control ring 228 becomes 8 steps.

In this state, when the magnet connected to the sector close lever 246is turned on, thereby the stepping motor rotating to rotate the lowergear 232a-1 clockwise by 9 steps, the focus control ring 218 is returnedto the initial position. However, since the exposure control ring 228 isin a state where it is rotated by further 1 step, the stepping motor isrotated in an opposite direction by 1 step so as to return the exposurecontrol ring 228 to the initial position, and at the same time, the timedifference protrusion 236 comes to contact the slide protrusion,completing the initialization and turning off the magnet.

When the focus control ring and the exposure control ring rotatecounterclockwise and the stepping motor rotates by 4 steps, a normalexposure method is follows:

In step S125, it is determined whether the driving number of thestepping motor M is an even number step or an odd number step.

If the determined number is an even number step, in the step S135, thestepping motor M rotates with the even number step, and in the stepS145, the stepping motor rotates clockwise by 1 step.

In the above, since the time difference protrusion 236 of the speedreduction gear 232a contacts the slide protrusion 240, the rotatingforce is transmitted late to the focus control ring 18 by 1 step,thereby rotating the focus control ring 218 counterclockwise by 3 steps.

In this point, the exposure control ring 228 connected to the reductiongear 230 rotates clockwise by 4 steps while receiving clockwise rotatingforce.

At this state, to perform the exposure operation, when the lower gear232a-2 rotates counterclockwise by 1 step, the slide protrusion of theupper gear 232a-1 comes to contact the time difference protrusion 236,such that the focus control ring 218 does not rotate while the exposurecontrol ring 228 rotates clockwise by 1 step to allow the sectors to becapable of an opening state.

At this point, since the magnet 268 is controlled to an on state, thesector close lever 246 is restrained, and the sector open lever 248rotates by the biasing force of the elastic member 256, thereby openingthe sectors.

After completing the exposure operation, the magnet 268 is turned off sothat the sector open lever 246 can rotate to the close position by thebiasing force of the elastic member 254.

By rotating the stepping motor M clockwise by 1 step, the sector closelever 246 then rotates counterclockwise to make the rotation of theexposure control ring 228 free, thereby starting the initializingoperation.

At this point, since the time difference protrusion 236 of the lowergear 232a-2 contacts the slide protrusion 240 of the upper gear 232a-1,both the focus control ring 218 and the exposure control ring 228 rotateclockwise by 1 step. Therefore, each resultant number of rotating stepsof the rings 218 and 228 becomes 2 steps from the initial position.

In this state, when the mag net 268 is turned on and the lower gear232a-2 rotates counterclockwise by 2 steps by rotating the steppingmotor, both the focus control ring 218 and the exposure control ring 228are simultaneously returned to the initial position, and the timedifference protrusion 236 comes to contact the slide protrusion 240,thereby completing the initializing operation and turning off the magnet268.

When both the focus control ring and the exposure control ring rotatecounterclockwise and the stepping motor rotates by 7 steps, a normalexposure method is as follows:

In step S125, it is determined whether the driving number of thestepping motor M is an even number step or an odd number step.

If the determined number is the odd number step, in the step S135-1, thestepping motor M rotates by 7 steps.

In the above, since the time difference protrusion 236 of the speedreduction gear 232a contacts the slide protrusion 240, the rotatingforce is transmitted late to the focus control ring 218 by 1 step,thereby rotating the focus control ring 218 counterclockwise by 6 steps.

As a result, the time difference protrusion 240 comes to contact thetime difference protrusion of the lower gear 232a-2, and the sectorclose lever 246 comes to be in a state where it can rotate.

At this point, since the magnet 268 is controlled to an on state, thesector close lever 246 is restrained, and the sector open lever 248rotates by the biasing force of the elastic member 256, thereby openingthe sectors.

After completing the exposure operation, the magnet 268 is turned off sothat the sector open lever 246 can rotate to the close position by thebiasing force of the elastic member 254.

By rotating the stepping motor M counterclockwise, the sector closelever 246 then rotates counterclockwise to make the rotation of theexposure control ring 228 free, thereby starting the initializingoperation.

That is, in a state where the time difference protrusion 238 of thelower gear 232a-2 contacts the time difference protrusion 240 of theupper gear 232-1, by the 1 step rotation of the stepping motor M, thetime difference protrusion 236 comes to contact the slide protrusion 240and the exposure control ring 228 rotates clockwise by 1 step.Therefore, each resultant number of rotating steps of the focus controlring 218 and the exposure control ring 228 becomes 5 steps.

At this point, by controlling the magnet 268 to an on state and 6 stepsrotation of the stepping motor M counterclockwise, both the focuscontrol ring 218 and the exposure control ring 228 are simultaneouslyreturned to the initial position, and the magnet 268 is turned off.

A bulb exposure method will be described hereinafter with reference toFIGS. 24, 27 and 28 when the focus control ring and the exposure controlring rotate clockwise and the stepping motor rotates by 4 steps.

Bulb exposure differs from normal exposure in that the magnet 268 foradjusting the sector opening time cannot remain in an on state.Therefore, in a state where the sector close lever 246 is engaged withthe end 235' of the exposure control ring 228, after turning off themagnet and exposing as much as the bulb time, the initializing operationstarts.

At the initial position, the time difference 36 provided on the lowergear 232a-2 of the speed reduction gear 232a contacts the slideprotrusion 240 provided on the upper gear 232a-1 (step S210).

It is determined if the driving direction of the stepping motor M is aclockwise direction or counterclockwise direction (step S220). If thedriving direction is in the clockwise direction, it is next determinedif the driving step of the stepping motor is an odd number or an evennumber (step S230).

If it is determined that the driving step rotates clockwise by 4 steps,since the time difference protrusion 236 is in a contact state with thetime difference protrusion 240, the rotating force of the stepping motoris transmitted to the focus control ring 218, thereby rotating the focuscontrol ring as much as the measured distance amount (step S240).

At this point, the exposure ring 228 connected to the exposure speedreduction gear 230 receives clockwise rotating force and rotates by 4steps.

By the above operation, as completing the focus control, the magnet 268is controlled to an off state to maintain the sectors open state as muchas the preset bulb time (step S250).

Therefore, the sector open lever 248 rotates to open the sectors, and inthis state, after a predetermined amount of time passes, the magnet 268is turned off.

To close the sectors, when rotating the stepping motor M clockwise by 1step after completing bulb exposure for closing the sectors (step S260),the sector close lever 246 comes to be released from the end 235' of thefocus control ring 228. At this state, when controlling the magnet 268to an off state (step S270), the sectors are closed by the biasing forceof the elastic member 254 of the sector close lever 246.

And then, for the initializing operation, the lower gear 232a-1 isrotated counterclockwise by 1 step (step S280), and the magnet 268 isturned on (step S290).

By this operation, since the resultant number of rotating steps of thespeed reduction gear becomes 6 steps in the clockwise direction, thespeed reduction gear should rotate counterclockwise by 6 steps for theinitialization.

However, since the slide protrusion 240 of the upper gear 232a-1contacts the time difference protrusion 236 of the lower gear 232a-2,when rotating counterclockwise by 6 steps, there is an error by 1 stepwhen driving the focus control ring 218.

To compensate for the error, after rotating the lower gear 232a-2clockwise, which positions the focus control ring 218 to the initialposition by rotating it counterclockwise by 6 steps, when rotating thereduction gear 232a counterclockwise by 1 step to return both the speedreduction gear 232a and the exposure control ring 228 to the initialposition, the time difference protrusion 236 and the slide protrusion240 is displaced to the initial position and thereby the exposurecontrol ring 228 is also returned to the initial position (step S300).

In this state, the electric power which has been applied to the magnet268 is turned off, thereby completing the exposure control (step S310).

When the focus control ring and the exposure control ring rotateclockwise and the stepping motor rotates by 7 steps, a bulb exposuremethod is as follows.

At the initial position where the time difference 236 provided on thelower gear 232a-2 of the speed reduction gear 232a contacts the slideprotrusion 240 provided on the upper gear 232a-1, if it is determinedthat the driving step of the stepping motor M is clockwise 7 steps (stepS240-1), the lower gear 232a-2 rotates counterclockwise by 7 steps, andthe both the focus control ring 218 and the exposure control ring 228rotate clockwise by 7 steps.

For bulb exposure, the focus control ring 218 does not rotate and thereduction gear 232a rotates clockwise by 1 step such that the sectorclose lever 246 can be engaged with the end 235' of the exposure controlring 228.

By this operation, the focus control ring 218 does not rotate, and theexposure control ring 228 rotates counterclockwise by 1 step such thatthe sectors can open and the time difference protrusion 238 comes tocontact the slide protrusion 240.

In this state, to maintain the sector opening time as much as thepredetermined bulb time, when turning the magnet 268 off, the sectoropen lever 248 rotates to completely open the sectors.

At this point, since the sector close lever 246 cannot moved by beingengaged with the end 235' of the exposure control ring 228, the bulbexposure is realized.

Since this state is that the exposure control ring further rotatescounterclockwise by 1 step, the resultant rotation becomes 6 steps andthe time difference protrusion 238 comes to contact the slide protrusion240.

After completing bulb exposure, the magnet 268 is controlled to an onstate. At this state, to close the sectors, the lower gear 232a-2further rotates counterclockwise by 1 step so that the sector closelever 246 can be disengaged with the end 235' of the exposure controlring 228. When the magnet 268 is then turned off, the sector close leverrotates to close the sectors.

It this state, when rotating the lower gear 232a-2 counterclockwise by 1step and turning the magnet 268 on, the resultant rotation of the lowergear 232a-2 becomes 8 steps.

Here, by rotating the speed reduction gear 232a clockwise by 8 steps,initialization is realized.

However, when the speed reduction gear rotates clockwise in a statewhere the time difference protrusion 236 of the speed reduction gear232a contacts the slide protrusion 240, an error occurs by 1 step whendriving the focus control ring 218. To compensate the error, afterrotating the lower gear 232a-2 clockwise by 9 steps and returning thefocus control ring 218 to the initial position, when rotating the lowergear 232a-2 counterclockwise by 1 step to return both the speedreduction gear 232a and the exposure control ring 228 to the initialposition (step S300), the time difference protrusion 236 rotates to theinitial position where it contacts the slide protrusion 240, and theexposure control ring 228 is also returned to the initial position.

When the focus control ring and the exposure control ring rotatecounterclockwise and the stepping motor rotates by 4 steps, a bulbexposure method will be described hereinafter.

If the driving direction is the counterclockwise direction (step S220),it is next determined if the driving step of the stepping motor is anodd number or an even number (step S230).

If it is determined that the driving step is counterclockwise 4 steps(step S245), since the 4-step clockwise rotation of the lower gear232a-2 rotates the upper gear 232a-2 and the time difference protrusion240 after their 1-step rotation, the focus control ring 218 rotatescounterclockwise by 3 steps.

Since the time difference protrusion 238 is in a contact state with theslide protrusion 240, to maintain the predetermined sector opening timeas much as the pre-set bulb open time, when turning the magnet 268 off,the sector open lever 248 rotates to completely open the sectors. Thisopen state is maintained for as long as the bulb time.

In a state where the magnet 268 is turned on, when rotating the lowergear 232a-2 counterclockwise by 1 step to release the exposure controlring 228 from the sector close lever 246 and when turning the magnet 268off, the sector close lever 246 pushes the sector open lever 248,thereby closing the sectors and completing the bulb photographing.

At this state, the initialization starts by turning the magnet 268 onafter rotating the lower gear 232a-2 counterclockwise.

By this control, the resultant rotation of the lower gear 232a-2 becomesclockwise 2 steps.

When the focus control ring and the exposure control ring rotatecounterclockwise and the stepping motor rotates by 7 steps, a bulbexposure method is as follows.

In step S235', it is determined that the driving step of stepping motorM is an odd number (7 steps), from the initial position where the timedifference protrusion 236 of the speed reduction gear 232a contacts theslide protrusion 240, the focus control ring 218 rotates after 1 step ofthe motor. Accordingly, the resultant number of rotating steps of thefocus control ring 218 becomes 6 steps.

At this point, since the exposure control ring 228 rotatescounterclockwise by 7 steps, for bulb exposure, the exposure controlring 228 rotates clockwise by 1 step in a state where the focus controlring 218 does not rotate, such that the sector close lever 246 can beengaged with the end 235' of the exposure control ring 228.

By this operation, the lower gear 232a-2 comes to rotate by 1 step, andthe time difference protrusion 238 comes to contact the slide protrusion240.

After this, to maintain the sector opening time as much as the pre-setbulb time, the magnet 268 is turned off and the sector open lever 248rotates, thereby completely the opening of the sector open lever 248.

After opening the bulb for a predetermined time, the magnet 268 isturned on, the lower gear 232a-2 rotates counterclockwise by 1 step torelease the sector close lever 246 from the end 235' of the exposurecontrol ring 228, and the magnet 268 is turned off again.

By this operation, since the sectors are closed while the sector closelever 246 rotates, bulb exposure is completed.

In this state, initialization starts by controlling the magnet 268 to anon state after the speed reduction gear 232a rotates counterclockwise by1 step.

At this point, the speed reduction gear 232a rotates clockwise by 7steps for the focus control, counterclockwise by 1 step to maintain thesectors in a bulb state, counterclockwise by 1 step to close thesectors, and counterclockwise by 1 step for initialization. Therefore,the resultant rotation of the speed reduction gear 232a becomes 4 stepsfrom the initial position.

The focus control ring 218 rotates by the speed reduction gear 232acounterclockwise by 6 steps, rotates clockwise by 1 step to close thesectors, and rotates clockwise by 1 step for initialization. Therefore,the resultant rotation of the focus control ring becomes 4 steps.

The exposure control ring 228 rotates counterclockwise by 7 steps forthe focus control, clockwise by 1 step for exposure, clockwise by 1 stepto close the sectors, and counterclockwise by 1 step for initialization.Therefore, the resultant number of rotating steps of the exposurecontrol ring 228 becomes 4 steps.

At this point, since the time difference protrusion 236 of the speedreduction gear 232a contacts the slide protrusion 240, for theinitialization, the stepping motor M rotates clockwise by 4 steps torotate the lower gear 232a-2 counterclockwise by 4 steps, completinginitialization. Finally, the magnet 268 is controlled to an off state.

What is claimed is:
 1. A method for driving an electronic shutter of acamera, comprising the stages of:setting an initial focus of a rotatingmember co-axial and connected with a focus control lens in a state wheresaid focus control lens is pre-set in a middle position between amaximum position and a minimum position of a whole focusing region, suchthat the initial position of a focus control lens is positioned in amiddle step between a focus position of said focus control lens withrespect to a pre-set farthest subject and a focus position of said focuscontrol lens with respect to closest subject; controlling focus byrotating the rotating member connected to a first driving means in aclockwise or counterclockwise direction from an initial position, inorder to move said focus control lens to a focused position setaccording to a value calculated by a distance measuring means when ashutter switch is operated; and performing exposure by operating sectoropening/closing means according to an exposure value calculated by aluminescent measuring means, and connecting sectors, which are biasedthrough an elastic member, with second driving means rotating in eitherdirection, depending on the application of current, when controllingfocus of said focus control lens is finished.
 2. A method for driving anelectronic shutter of a camera in which a focus control lens moves to afocus position and is connected to an exposure control ring to performan opening and/or closing of sectors, comprising the stages of:settingan initial position so that a focus control ring is located at a pre-setinitial position by determining the position of said focus control ringco-axial with and connected to said focus control lens by the use of aninitial position detecting/adjusting means, in a state where said focuscontrol lens is disposed in a middle position between a focus positionsaid focus control lens with respect to a pre-set farthest subject and afocus position of said focus control lens with respect to a pre-setclosest subject, wherein said positions are separated by distanceincrements defined as steps, such that the initial position of saidfocus control lens is positioned in a middle step among all the steps offocus control position; adjusting focus position, multi-step zoomingsaid focus control lens toward sectors or subjects by rotating the focuscontrol ring clockwise or counterclockwise when viewed from the positionof the subject, the focus control ring including a speed reduction gearand rotating in the same direction as that of an applied power source tomove said focus control lens; and performing exposure according to anexposure value calculated by a luminescent measuring means by openingsectors, which are biased in a closed state through an elastic member,by an automatic exposure meter overcoming the biasing force, wherein theautomatic exposure meter rotates in a certain direction according to theapplication of current, and by closing said sectors by the returningforce of the elastic member according to the application of a reversedcurrent to said automatic exposure meter.
 3. A method for driving anelectronic shutter of a camera according to claim 2, wherein the powersource of a first driving means rotates by 90 degrees per one-step ofdriving.
 4. A method for driving an electronic shutter of a cameraaccording to claim 2 or 3, wherein a stabilized region of a steppingmotor is set while applying a power supply to an automatic exposuremeter at a point that adjustment of the focus position is finished bystopping of the focus control ring.
 5. A method for driving anelectronic shutter of a camera according to claim 4, wherein saidstabilized region of the stepping motor is set by at least 20 ms.
 6. Amethod for driving an electronic shutter of a camera according to claim2, wherein the initial position of the focus control ring is set by aphoto interrupter which detects the changed position of said focuscontrol ring, and rotates said focus control ring in a close directionto the initial position by driving said power source.
 7. A method fordriving an electronic shutter of a camera according to claim 2, whereinsaid focus control lens is zoomed toward sectors or the subject by alinear moving lens holder meshed with said focus control ring andslideable relative to said focus control ring, the rotation of the lensholder being interrupted by a motor cover member when said focus controlring rotates in a clockwise or counterclockwise direction to move saidlens holder.
 8. A method for driving an electronic shutter of a cameraaccording to claim 2 or 7, wherein a lens barrel integrally combinedwith the lens holder is elastically supported to be biased always towardthe subject, including an elastic member in order to remove a gap errorwhich occurs in a combination of teeth of the focus control ring andlens holder.
 9. A method for driving an electronic shutter of a cameraaccording to claim 2, wherein the automatic exposure meter rotates inone direction, overcoming the biasing force, and rotates a sector leverhaving teeth when electric power is applied, such that sectors connectedwith the sector lever thereof are opened.
 10. A method for driving anelectronic shutter of a camera according to claim 2, wherein slots ofsectors opened by the automatic exposure meter measure correspondingslots formed in a shutter base through a photo reflector, and sets astarting point, to control an exposure value calculated by theluminescent measuring means.
 11. A system for driving an electronicshutter of a camera, comprising:a first driving means including a powersupply; a rotation member meshing with said driving means, co-axial andconnected to a focus control lens, rotating in the same direction as thepower supply, and zooming the focus control lens in response to a valuecalculated by a distance measuring means; means for detecting andadjusting an initial position of the rotation member which adjusts saidrotation member to a set initial position when said rotation member isnot positioned in a middle position between a maximum zooming positionand a minimum zooming position when initial power supply is applied tothe camera; and second driving means for opening/closing sectors whichare driven according to an exposure value calculated by a luminescentmeasuring means when a power supply is applied, while keeping sectorsclosed, biased by an elastic member.
 12. A system for driving anelectronic shutter of a camera, having means for setting an initialposition for a focus control lens at a position between a focus positionof said focus control lens regarding a pre-set farthest subject and afocus position of said focus lens regarding a pre-set closest subject,said system comprising:a power supply; a reduction gear portion meshingwith said power supply, and transmitting a rotating effect thereof; afocus control ring co-axial and connected with the focus control lens,meshing with said reduction gear portion, rotating in the same directionas said power supply, and zooming a lens holder integrally combined witha lens barrel with the rotating effect to a position determined by acalculation value calculated by distance measuring means; a photointerrupter for detecting a changed position of the focus control ring,and for returning said focus control ring to an initial position byoperating the power supply; an automatic exposure meter which is biasedtoward one direction by an elastic member, and which is rotated orreturned in the opposite direction to overcome the biasing force of saidelastic member; and a sector lever, connecting with the rotation of saidautomatic exposure meter, and opening/closing sectors.
 13. A system fordriving an electronic shutter of a camera according to claim 12, whereinthe lens holder is threadingly connected with the inner circumferentialsurface of the focus control ring.
 14. A system for driving anelectronic shutter of a camera according to claim 12, wherein arotation-preventing lug formed on the outer circumferential surface ofthe lens holder moves slidably within a rotation-preventing grooveformed on the motor cover.
 15. A system for driving an electronicshutter of a camera according to claim 12 or 14, including an elasticmember for elastically supporting the lens barrel on the motor cover.16. A method for driving an electronic shutter of a camera, including afocus control lens for controlling focus, comprising the stagesof:setting an initial position for the focus control lens at a positionbetween a focus position of said focus control lens regarding a pre-setfarthest subject and a focus position of said focus control lensregarding a pre-set closest subject; controlling focus by rotating saidfocus control ring, co-axial with said focus control lens and connectedwith driving means, in one direction or an opposite direction to movesaid focus control ring to a pre-set position determined according to acalculation value calculated by a distance measuring means when ashutter switch is operated; and performing exposure according to anexposure value calculated by a luminescent measuring means by operatingsector opening/closing means, stopping the exposure control ring, whichis rotated in the same direction as the focus control ring by a drivingmeans, with the focus control ring at a locking-released position of thesector opening/closing means when controlling the focus of said focuscontrol lens is completed.
 17. A method for driving an electronicshutter of a camera, in which the focus control lens connected with thefocus control ring moves to a focus position, and opening/closing ofsectors is performed by connection of an exposure control ring,comprising the stages of:setting an initial position of said focuscontrol ring which drives said focus control lens, disposing said focuscontrol lens at a middle position between a focus position of said focuscontrol lens regarding a pre-set farthest subject and a focus positionof said focus control lens regarding a pre-set closest subject, whereinsaid positions are separated by distance increments defined as steps,such that the initial position of zooming for said focus control lens ispositioned in a middle step among all the steps; adjusting the focusposition, multi-staged moving said focus control lens toward sectors ora subject by rotating said focus control ring in one direction or anopposite direction to perform focus control for said focus control lens,said direction of rotation dependent on a calculation value calculatedby a distance measuring means when the shutter switch is operated;performing exposure by:a) starting an exposure operation by positioningthe exposure control ring, which is rotated and includes projections andgrooves alternatingly spaced along its outer circumference withprojection ends formed on the projections to lock a sector closinglever, such that a sector opening lever can be disposed on theprojections, and b) closing and opening the sectors in response to anexposure value calculated by a luminescent measuring means by stoppingthe exposure control ring and the focus control ring at a point wherethe exposure control ring rotates one step in an opposite direction whenthe sector closing lever is engaged by the projection end of theprojection; and initializing the system, returning said focus controlring and said exposure control ring to a point that said sector closinglever is biased on the projection end of the projection of the exposurecontrol ring after the exposure has been performed such that saidexposure control ring is again rotated by one step in the oppositedirection.
 18. A method for driving an electronic shutter of a cameraaccording to claim 17, wherein said focus control ring stops after onestep, and rotates, when the direction of driving means is reversed. 19.A method for driving an electronic shutter of a camera according toclaim 17 or 18, wherein the initial position is set such that the focuscontrol ring is directly connected during clockwise rotation of thedriving means, and is stopped by one step in the counterclockwisedirection.
 20. A method for driving an electronic shutter of a cameraaccording to claim 17, wherein a power supply of a driving means rotates90 degrees for every driving step.
 21. A method for driving anelectronic shutter of a camera according to claim 17, wherein the sectoropening lever as a component of the sector opening/closing means isbiased on a projection end formed on the outer circumferential surfaceof said focus control ring at an initial position of said focus controlring such that movement error of sectors caused by outer shocks isprevented.
 22. A method for driving an electronic shutter of a cameraaccording to claim 21, wherein said focus control lens maintains theinitial position despite rotation of said focus control ring in a regionthat the projection end of the focus control ring biases the sectoropening lever.
 23. A method for driving an electronic shutter of acamera according to claim 21, wherein the sector opening lever rotatesin a direction to open the sectors when its engaged state is released bythe projection said focus control ring which rotates slower than therotation speed of one step of said exposure control ring by speedcontrol means, moving along the outer circumferential surface of thegrooves and projections of said exposure control ring.
 24. A method fordriving an electronic shutter of a camera according to claim 17, whereinsaid sector closing lever of the sector opening/closing means is biasedby an exposure control magnet, said magnet being turned on when ashutter switch is operated, and closing the sectors at a time determinedaccording to an exposure value calculated by the luminescent measuringmeans.
 25. A method for driving an electronic shutter of a cameraaccording to claim 17 or 24, wherein, after automatic exposure isperformed, said exposure control ring magnet is turned on when saidsector closing lever is biased on a projection end of a projection ofsaid exposure control ring by one step in a clockwise direction of saidexposure control ring, and said exposure control ring magnet is turnedoff when said exposure control ring is returned to the initial position.26. A method for driving an electronic shutter of a camera according toclaims 17, 23, or 24, wherein the sector opening lever stops after saidfocus control ring performs focus control, and opens sectors by rotatinga sector drive pin clockwise according to the stopping of said exposurecontrol ring when said sector closing lever is positioned on theprojection of said exposure control ring, and said exposure controlmagnet is engaged by said sector closing lever.
 27. A method for drivingan electronic shutter of a camera according to claim 17, includingrotating said exposure control ring again by one step in the oppositedirection to an initialized direction at the point that automaticexposure is performed, and initializing the focus control ring byreturning to the opposite direction, so as to be directly connectedduring the clockwise rotation of the power supply constituting drivingmeans to set the initial position.
 28. A method for driving anelectronic shutter of a camera according to claim 17, wherein exposureis performed according to an exposure value calculated by luminescentmeasuring means, and includes stopping the exposure control ring withsaid focus control ring when the sector opening/closing means aredisposed on projection release locking, and rotating the sectoropening/closing means by one step in the opposite direction when engagedby the projection end of said projection, to perform automatic exposureaccording to an exposure value incident from the subject, in a statethat adjustment for the focus position is performed.
 29. A method fordriving an electronic shutter of a camera according to claim 17, 23, or24, including performing bulb exposure by closing sectors with therotating effect of said sector closing lever when said sector closinglever is positioned on the groove of the exposure control ring with onestep clockwise rotation of said exposure control ring, totally openingsectors by clockwise rotation of said sector opening lever, stoppingsaid exposure control ring with the focus control ring in a state that,after adjustment for the focus position is performed, said closing leveris biased on the projection end of a projection of said exposure controlring and said exposure control ring is biased on the projection end ofthe projection with a one step further rotation in the oppositedirection when said sector closing lever is not positioned on theprojection end of the projection of said exposure control ring.
 30. Amethod for driving an electronic shutter of a camera according to claim29, including engaging the sector closing lever by said exposure controlmagnet being turned on when a shutter switch is operated, and saidsector closing lever turning said exposure control ring magnet off whenit is biased on the projection end of projection of said exposurecontrol ring such that sectors are totally opened.
 31. A system fordiving an electronic shutter of a camera, comprising,driving meansincluding a power supply and means for transmitting the rotating effectthereof; a focus control ring for zooming an exposure control lens to aposition determined by a calculation value calculated by a distancemeasuring means according to the rotating effect, said ring rotating inthe same direction as the power supply meshed with said driving means,and rotating, after stopping, for one step when the rotation directionof said power supply is reversed; an exposure control ring rotating inthe same direction as said power supply meshed with said driving means;and sector opening/closing means for opening/closing sectors accordingto an exposure value calculated by a luminescent measuring means, andreleasing locking by stopping the rotating action of both said focus andexposure control rings.
 32. A system for driving an electronic shutterof a camera, in which a lens connected with the focus control ring movesto a focus position, and opening/closing of sectors is performed inconnection with an exposure control ring, comprising:reduction meansrotating after stopping for one step, when the rotation direction ofsaid power supply is reversed, while transmitting the rotating effectmeshed with the power supply; a focus control ring for zooming anexposure control lens to a position determined by a calculation valuecalculated by a distance measuring means with the rotating effect, saidring rotating in the same direction as said power supply meshed with agear of said reduction means; an exposure control ring rotating in thesame direction as said power supply, being engaged with a gear includedbetween said power supply and said exposure control ring; a sectoropening lever for opening sectors, depending on the stopping of therotation action of said exposure control ring with the focus controlring; and a sector closing lever for closing sectors, depending on powerof an exposure control magnet being turned off at time determined by anexposure value calculated by a luminescent measuring means, and therelease of locking by said exposure control ring.
 33. A system fordriving an electronic shutter of a camera according to claim 21, whereinthe focus control ring consists of a projection end of the projection ofsaid focus control ring for biasing said sector opening lever to preventmovement error of sectors caused by outer shocks.
 34. A system fordriving an electronic shutter of a camera according to claim 33, whereinone end of the sector opening lever includes said sector driving pin,while the other end is meshed with the governor gear and isspeed-controlled by an anchor.
 35. A system for driving an electronicshutter of a camera according to claim 31, further comprising an elasticmember having a circumferential biasing force and a vertical biasingforce to prevent double opening of sectors.